A roller coaster starts from rest at point A. If you ignore friction and take the zero of potential energy to be at C, A) the kinetic energy of the coaster at D will be equal to its potential energy at A. B) the kinetic energy of the coaster at E will be equal to its potential energy at C. C) the kinetic energy of the coaster at C will be equal to its potential energy at A. D) the kinetic energy of the coaster at B will be equal to its potential energy at C E) None of these is correct. 13. Two objects are sliding at the same speed across a wooden surface. The coefficient of kinetic friction between the first object and the surface is twice that between the second object and the surface. The distance traveled by the first object before it stops is S. The distance traveled by the second object is A) impossible to determine without knowing the masses involved. B) 28 C) S/2 D) S E) 4S 14. A person of weight w is in an upward-moving elevator when the cable suddenly breaks. What is the person's weight measured in the elevator immediately after the elevator starts to fall? A) w B) greater than w C) less than w D) 9.81w E) zero A force F produces an acceleration a on an object of mass m. A force 3F is exerted on a second object, and an acceleration 8a results. What is the mass of the second object? A) 3m B) 9m C) 24m D) (3/8)m E) (8/3)m 15.